Pushing Boundaries With New Technology

We took a look at new developments for dealing with brownout scenarios, sound reduction, data management and more.

By Charlotte Adams

It’s not good when a pilot loses situational awareness in a dust cloud near the ground. Brownout is a major threat to helicopters in Iraq and Afghanistan. The U.S. Department of Defense has estimated that 37 percent of helicopter losses there between 2001 and 2008 involved brownout and obstacle strikes. This article looks at pilot brownout aids and other emerging technologies.

Combat unit training scenarios must include a continuum of threat levels designed to train students to avoid, degrade, defeat or destroy threat systems in order to survive. Man-portable air defense systems (MANPADs), present one of the most lethal threats to helicopters since Vietnam. Training to deal with them impossible.

Pilot Brownout Aids

The CH-47F’s hover display, in combination with the aircraft’s digital automatic flight control system, helps to correct for uncommanded lateral and vertical movement in low-visibility conditions. Rockwell Collins’ Common Avionics Architecture System (CAAS) display provides real-time cuing to increase situational awareness and help pilots to visualize the direction and rate of drift. In brownout, the display helps them to correct for drift and “beep” the aircraft down to the ground in controlled one-foot increments.

The “god’s eye view” display presents position, velocity and acceleration information relative to the desired hover point. Position information is depicted by two scalable concentric circles and radar altitude. Velocity and acceleration, depicted with a velocity vector line and an acceleration cue in the center of the display, help the pilot visualize the rate and direction of drift. The pilot uses the cyclic to keep the velocity vector and the acceleration cue inside the hover box.

The system does not feature an active sensor to paint the landing zone. “The pilots need to see where they are landing as they approach the landing zone before it is obscured by dust,” to verify that the area is clear of obstacles, said Doug Schoen, principal marketing manager with Rockwell Collins Government Systems. But the display helps the pilot to precisely hover over a spot and land without drifting, thanks to real-time inputs from the aircraft’s embedded GPS/INS. Schoen was not aware of any system in operational use by U.S. forces—other than FLIRs—that detects and displays obstacles.

Rockwell Collins is also developing “synthetic-enhanced vision” (SEV) for rotorcraft, combining synthetic vision (SV) technology with real-time sensor inputs. It has assembled an SEV testbed embedded in the CAAS architecture and demonstrated its functions. The system provides an out-the-window view of the terrain ahead, including obstacles, with a forward field-of-regard of 56 degrees. The company expects to have the equipment installed on an actual aircraft for internal flight test some time this year.

Active Sensor Input

One solution for brownout available today is Elbit’s Dust-Off, which integrates a number of off-the-shelf components already in use:

• SWORD (Surveillance and Warning Obstacle Ranging and Display) ladar (laser detection and ranging), which provides a real-time update to the digital terrain elevation database (DTED) throughout the flight, an 8-second warning of flight path obstacles in sharp turns and 12-second warning in straight flight; and

• Digital video recorder and mission data loader.

BVI Sound Reduction

Eurocopter has developed technologies to reduce the noise generated from blade-vortex interaction (BVI), which occurs when a rotor blade collides with the tip vortices shed from a previous blade. BVI causes a rapid, impulsive change in the loading on the blade, resulting in the typical flap-flap noise heard during descent, explained Yves Favennec, Eurocopter’s vice president of research and innovation. The concepts should be adaptable to any helicopter.

The company has developed a passive and an active approach to BVI noise reduction, known as Blue Edge and Blue Pulse, respectively. Blue Edge uses a double-swept blade while Blue Pulse employs active trailing-edge flaps integrated into the blades, along with a closed-loop system to control them. Blue Pulse also is intended to reduce vibration. In flights of Blue Edge on an EC155 testbed, Eurocopter claims to have demonstrated noise reductions of 3 to 4 dB, a more than 50 percent decrease. Tests of Blue Pulse on an EC145 have shown a noise reduction of up to 5 dB, according to the company. Vibrations have been decreased up to 70 percent for various flight conditions, providing “an almost jet-smooth” ride, Eurocopter said.

The idea of the curved rotor blade is that the blade tips should avoid simultaneous impact with the vortices from the preceding blades. Instead of having the tips encounter this turbulence at the same time, they hit it at slightly different times, reducing noise.

Blue Pulse, by contrast, employs piezo-driven flap modules on the trailing edge of each rotor blade. Movement of these flaps at a rate of 15 to 40 times per second “completely neutralizes the [BVI] noise typically associated with helicopters during descent,” the company said. The control input to the flaps is adapted automatically to the specific aircraft’s conditions to allow a global reduction of BVI noise, according to Eurocopter.

Although the active system is more complex than the passive one and will probably be more expensive to implement, it reduces noise by a greater margin and allows more flexibility in the angle of descent. Helicopters would be equipped with one or the other technology, not both. Flight testing of both systems continues: the company has not yet fixed a date for serial production. See Blue Edge image on this page.

Introduced in 2008, Dust-Off has undergone two simulator evaluations and one flight evaluation, according to Benjamin Weiser, senior director for U.S. and UK business development for Elbit’s Helicopter Upgrade business line. The ladar was flight tested last year as part of an agreement with the U.S. Army’s Aviation Applied Technology Directorate.

It is not clear whether any customers are using the whole Dust-Off system operationally at this time, but the company in late March was on the verge of signing its first production contract for the HMD component with 3D reference cues to allow drift detection and correction in low-visibility conditions. The symbology for drift detection and correction is derived from the embedded GPS/INS and other onboard sensors. In the full configuration, the symbols also can be derived from the ladar data, as it is tied to the geo coordinates through GPS/INS. These virtual reference symbols, or icons, which do not correspond to objects in the real world, also provide cues to altitude, attitude, airspeed and angle of approach. We don’t use “highway-in-the-sky” type symbology, Weiser said. “We’ve found that the pilots are so intent on keeping in those square boxes that they disregard everything else in their surrounding environment.” The company also noted that SWORD data can generate a “pure, lean and mean” symbolic presentation of categorized obstacles on the Israeli version of the ANVIS/HUD HMD, “as per the IAF [Israeli Air Force] requirements.” The IAF was preparing for SWORD acceptance test procedure flights in late March.

Dust-Off’s ladar scans the area in a forward-cone field-of-regard of about 100 degrees. In brownout landing mode the beam scans down to the ground to clear the landing zone and identify obstacles. The sensor scans millions of times per minute and each ping is measured in lat/long and elevation. Key information created from the three-dimensional ladar data and entered into the DTED is extracted from the DTED and presented as symbols on the helmet-mounted display, properly located within the pilot’s field-of-view. These include icons representing the location of hills, mountains, towers, and high and low wires. The system can identify 5mm wires at one kilometer and a high-power line at two kilometers, Weiser said.

Key to Dust-Off is its ability to add real-time terrain and obstacle data to the pre-stored terrain elevation database. Approaching the landing zone, a helicopter may encounter “all sorts of hustle and bustle—trucks coming in, refueling tanks,” Weiser said. The laser radar scanning and presentation capability gives pilots confidence that they are seeing the real-time scene, not a database rendering that is a month old. Elbit is also providing an additional, very precise radar altimeter to “ensure, as the pilot gets close to the ground, that the [obstacle] symbols are attached to the ground,” at the exact location, not floating above or beyond it. Dust-Off’s monocular HUD—positioned over the pilot’s right eye—provides a 32-degree circular field-of-view. Elbit has experimentally projected map data on the HMD, but “the jury is still out whether it’s too much of a soda straw vision,” too narrow a field-of-view for so much data. Besides the daytime HUD, Elbit provides a night solution that attaches to one of the objective ends of the night vision goggles.

Honeywell is deeply involved in military and civil R&D concerning low-visibility operations. The company took part in the now-complete Defense Advanced Research Projects Agency (DARPA) Sandblaster program, which focused on the desert brownout landing problem. Team leader Sikorsky provided the automatic flight controls, Honeywell contributed synthetic vision and a “sensor-driven, localized external evidence knowledge grid,” and Sierra Nevada supplied a 94-GHz millimeter-wave radar. The evidence grid is a 3D virtual model that overlays the sensor returns on top of the terrain database.

A representative Sandblaster display shows a perspective view the pilot would see, as if out the window, approaching an obscured landing zone. The landing zone is depicted as a cyan circle whose size is the same as the helicopter’s blade space. The triangle in the center represents the tricycle gear landing wheels of the Black Hawk (the JUH-60A Sandblaster demonstration vehicle). Using the Sikorsky flight control system and a control on the cyclic, the pilot moves the cyan circle around so that it’s not touching any obstacles that are painted yellow or red, according to their threat level. (Yellow indicates that the object is two feet high; red indicates that the object is four feet high.) The dark green circle below the cyan circle represents the sweep of the blades at the aircraft’s current position. A boulder on the right edge of this area is colored green because it is less than two feet high. The millimeter-wave radar provides data accurate from one to three feet.

Honeywell now is focusing on a Sandblaster follow-on program being planned by DARPA and the Air Force Research Lab (AFRL) to further develop the technology for forward-flight applications, beyond a landing-only solution.

Separately, the company expects to field a dedicated helicopter Cable Warning and Obstacle Avoidance (CW/OA) system in late 2012, built around its certified SV software, proven Enhanced Ground Proximity Warning System (EGPWS) terrain database and evidence grid.

It is also developing a less than 20-pound millimeter-wave radar, slated to roll out before the end of 2012, which will be offered as a CW/OA option, said Gregory Walters, marketing manager for crew interface. The product is designed to detect 3/8-inch cables at 2,000 feet with an 8-second response window, assuming speeds of 80-90 knots.

Honeywell is also working with a European partner to potentially integrate a lidar (light detection and ranging) sensor with the CW/OA.

CAE is developing a somewhat analogous real-time sensor-aided, augmented visionics system (AVS) as a brownout aid. Built on the company’s SV system, which sits atop CAE’s common database (CBD), AVS allows real-time updates of the synthetic world by sensors such as lidar, IR or cameras. Although AVS is sensor-agnostic, “lidar today is the most dust-penetrating sensor we know of,” said Adolfo Klassen, CAE’s chief technology officer. The company has demonstrated AVS with the Neptec Design Group’s lidar and also with a FLIR.

Passive Solution

TerraMetrics has been working with AFRL, using two visible-light cameras for stereoscopic ranging. The technique builds a real-time model of the landing zone as the aircraft approaches it, said Greg Baxes, company president. The data can be displayed to the pilot on a HUD or LCD. Most importantly for this project, the cameras give off no emissions. IR cameras could also be used.

Stereoscopic ranging uses pictures of the ground to compute the distances of objects in the image. That data is then projected into a terrain model, which is used in an SV system to display a real-time, 3D view to the pilot. The company is halfway through the second phase of its AFRL work and is conducting aerial testing on an early prototype using non-aircraft means.

The “store and remember” system starts taking images 1,000 feet out. “Unlike a laser that is working throughout the landing, we’ve done our hard work” before brownout starts, at about 100 feet or more off the ground, Baxes said. At that point you have the model and know the location and the attitude of the aircraft.

Rotorcraft Business Cents

Bristow Group and Appareo Systems have launched a mobile computer-based fleet management application that could save the oil and gas transportation company big bucks. The fleet management device (FMD) is not hard-wired into the airplane and is turned off during flight. It will automate the front-end of the billing process and speed certain pilot calculations. The FMD has gone live in Bristow’s approximately 14-helicopter Trinidad unit and was to begin incremental roll-out in the Gulf of Mexico on May 1, 2010. The company is already getting some productivity out of it, said Candace Gaspard, director for global IT application development.

The application is primarily a business tool to help pilots who fly many legs a day keep track of the passengers and equipment they carry to various destinations, as well as fuel on board. At the end of the day the pilot enters post-flight information into the FMD, docks the unit and downloads the data into back-end systems over a secure Internet link. (Bristow has also updated its back-end invoicing system.) With manual pilot reporting, by contrast, there could be a two-to-three-day delay in getting the data into the system, Gaspard said. The paperwork has to be trucked from the bases to the main location and then keypunched in. Any discrepancies or unreadable handwriting further delay the process.

Eventually Bristow would like to use the FMD “through the whole cycle flow,” Gaspard said. After the pilot returns to base, enters post-flight information and downloads the data, for example, the maintainer would complete his tasks, log the information into the device and download it, as well. The FMD is also a safety device, with preflight weight-and-balance and center-of-gravity calculations plus fuel and route planning. The three-pound, ruggedized Getac computer features an 8.4-inch-diagonal LCD touch screen.

Appareo’s fleet management device is a business tool and a safety device. Appareo Images

In Bristow’s application, Appareo programmed in their fleet and aircraft characteristics, as well as Bristow’s main landing locations. The pilot selects the base, drops in the waypoints, and the computer calculates the distance, ETA and required fuel. The FMD has a screen for inputting fuel, and the software won’t allow the pilot to continue calculations if insufficient fuel has been entered, said Ben Wright, Appareo’s vice president of sales and marketing.

Although the application was designed with Bristow inputs, the basic software has potential for additional functions and wider use, Wright said. The company has seen interest from small fleet operators that want to shorten their cash collection process cycle. In many operations, particularly in the helicopter industry, the billing cycle is still very much paper-based, he said.

New Image Recorder

With image recording No. 2 on the NTSB’s Most Wanted List, OuterLink is offering a rotorcraft solution. OuterLink, which began with satellite-based tracking, has developed a Flight Data System (FDS), including voice and video recording, integrated satcom, data acquisition and quick access recorder functions. It is pursuing STCs for the FDS on the Eurocopter EC135 and the EC145, said Jeff Warner, vice president of sales and marketing.

OuterLink also has developed Safety Matrix And Reporting Threshold (SMART) software. SMART allows customers to define up to 10 events and use up to 10 parameters or conditions to characterize each event. In combination with the satcom system, SMART can send a text message alert to a phone or email address. This allows “live FOQA,” Warner said. The company has teamed with Flightscape, a unit of CAE, to provide FOQA software.

STARFlight, the Travis County, Texas, public EMS and rescue operator with three EC145s, uses OuterLink’s tracking, voice/video recording and QAR products, with plans to add the vendor’s multifunction data acquisition unit and the SMART interface, said Willy Culberson, director of operations. It wanted a cockpit video recording system because of the NTSB’s emphasis and for quality assurance reviews of its flight procedures. “We fly a single-pilot operation, so we can’t always have an instructor up with the pilot,” Culberson said. “We can review tapes to make sure the pilots are up to par.”

STARFlight pilots also use OuterLink’s satcom feature to send text messages to the communications center in order to close out flight plans when they are out of radio range. The flight tracking system allows communications center personnel to precisely locate aircraft in order to tell which aircraft is closest to an accident scene, assist in hospital pad coordination and avoid weather. GPS position, altitude, airspeed and heading information is updated every 30 seconds in non-emergencies and every five seconds in emergencies.

PMA Composite Blades

Replacing tail rotor blades on Bell 206s and UH-1s with higher-performance PMA composite blades is big business for Van Horn Aviation (VHA). The company received an amendment from the FAA, adding the 206L series to its 206B composite tail rotor blade STC in February 2010. Featuring a NASA-developed airfoil, titanium root fittings and carbon fiber construction, the VHA 206 blades result in decreased noise, reduced pedal forces and double the retirement life (to 5,000 hours), compared to OEM blades, according to VHA.

VHA is working with Transport Canada for Canadian certification of the 206 tail rotor blades and has applied to FAA for an STC on the OH-58. The VHA blades are being flown on two OH-58s operated by the Pasadena, Calif., police department, which was interested in the blades for noise reduction. The company expected to receive both the Canadian and the OH-58 STCs in April. In addition to the 206 blades, VHA manufacturers a composite tail rotor blade for various models of the UH-1. The company is also designing composite main and tail rotor blades for the MD500, a composite main rotor blade for the 206 and tail rotor blades for the Bell 212.

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